Stack Overflow and Server Fault are both clearly for problems in their respective fields. As such, why is Super User to be called Super User? Is it because it too begins with an S? What were other names that were under consideration?
I think it might have to do with the other name for root. I suppose they could have called it root...but that would have sucked, IMO.
That, and yes, it begins with an S and has a nice acronym (SU). IIRC, the su in the nix sudo command used to mean superuser (today it's an acronym for "substitute user")...
So it's just nice all around.
Aside from SuperUser being an incredibly easy name to remember (good for business), it also gives off the impression that there are plenty of super users out there who know how to answer all your questions in lightning fast time.
But shouldn't superuser (which is the other name for root) be the name for what we currently call serverfault? I mean if that site is for sysadmins, superuser seems appropriate, whereas a site for the common "Internet Explorer is broken" type questions seems like we're giving them too much credit by calling them super users.
IIRC it was substantially because:
Joel and Jeff found or knew someone that owned the domain superuser.com and would sell it to them.
The domain was fairly appropriate to the subject matter.
... with (1) being a constraint on the options they actually had it was the best choice available to them.
Based on the Stackoverflow podcast (#59 or #60) Jeff was okay with Superuser breaking from the consistency of StackOverflow and ServerFault. He particularly talked about being okay with the inconsistent icon. It stands to reason that the thinking would extend to other aspects of the site (the title, we'll see where the other inconsistencies are).
If I recall correctly, there was a contest to name SU and SF where users submitted ideas as comments to the blog post in which it was annouced.
(I cannot seem to find a link to the post(s) now that I need it—isn’t that always the way? If someone has or can find a link to the blog post(s) with the submissions, feel free to add it.)
If they wanted to keep with the "failure" theme of the names for StackOverflow and ServerFault, they probably would have had to call SuperUser "BlueScreenOfDeath". =) Not as catchy as SuperUser, IMO.
Ultimately, for an internet site, doesn't it come down to a tradeoff between a name that describes what a website does versus the domain names that are available to be used?
In some of my other website ventures, I am often driven to choose a name simply because I can find a .com, .net or .org that is still available.
Apparently UserError.com must not have been available. :-)